Reading your post again............

On your last 3 coats of laying down your clear I would let set 24 hours dry time before any water sanding and buffing .
There will be alot of material that needs gassing off before the final step is done. Maybe even 48 hours.

I would hit the 1600 grit with 2000-3000 for your final sanding before buffing , bringing out the shine will be faster this way, less elbow grease

Another thing is get an air palm buffer ( like a dyna brade , not cheap but well worth it ), as bike plastic has some crazy bends and lines.

Spray